“Undefined Index” error

With the plugin activated, after logging in I get this error instead of my page:

Notice: Undefined index: provider in /wp-content/plugins/deeper-comments/lib/social-login/social-login-bws.php on line 112

Warning: Cannot modify header information - headers already sent by (output started at /wp-content/plugins/deeper-comments/lib/social-login/social-login-bws.php:112) in /wp-includes/pluggable.php on line 1355

My site doesn’t show any other errors and works properly without this plugin on. Any insight as to what could be causing this? All social share and social login options are turned off.